EventObject.java revision 49965c1dc9da104344f4893a05e45795a5740d20 
1/*
2 * Copyright (c) 1996, 2003, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package java.util;
27
28/**
29 * <p>
30 * The root class from which all event state objects shall be derived.
31 * <p>
32 * All Events are constructed with a reference to the object, the "source",
33 * that is logically deemed to be the object upon which the Event in question
34 * initially occurred upon.
35 *
36 * @since JDK1.1
37 */
38
39public class EventObject implements java.io.Serializable {
40
41    private static final long serialVersionUID = 5516075349620653480L;
42
43    /**
44     * The object on which the Event initially occurred.
45     */
46    protected transient Object  source;
47
48    /**
49     * Constructs a prototypical Event.
50     *
51     * @param    source    The object on which the Event initially occurred.
52     * @exception  IllegalArgumentException  if source is null.
53     */
54    public EventObject(Object source) {
55        if (source == null)
56            throw new IllegalArgumentException("null source");
57
58        this.source = source;
59    }
60
61    /**
62     * The object on which the Event initially occurred.
63     *
64     * @return   The object on which the Event initially occurred.
65     */
66    public Object getSource() {
67        return source;
68    }
69
70    /**
71     * Returns a String representation of this EventObject.
72     *
73     * @return  A a String representation of this EventObject.
74     */
75    public String toString() {
76        return getClass().getName() + "[source=" + source + "]";
77    }
78}
79